<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<!--独占一行-->
<div>div1</div>
<div>div2</div>
<div>div3</div>
<!--共占一行-->
<span>span1</span>
<span>span2</span>
<span>span3</span>

<h1>内容   标题</h1><!--多个空格只识别一个-->
<h1>内容 &nbsp;&nbsp;&nbsp;标题</h1>

&lt;abc&gt;
</body>
</html>